Selective breeding in rats for extreme densities of platelet 3H-imipramine binding sites: Evidence against a trait hypothesis

Abstract Some investigators suggest that the number of platelet 3 H-imipramine binding sites is genetically determined and that the reduced 3 H-imipramine binding observed in some studies of depression represents a trait marker. Others believe that 3H-imipramine binding is state-dependent because 3H-imipramine binding has been reported to normalize after clinical recovery. We used a genetic selection paradigm in rats to approach this question from another direction. While breeding 10 generations of rats, we used either extremely high or extremely low density of platelet 3 H-imipramine binding sites as a selection criterion. We were unsuccessful in producing two distinct rat sublines. These data do not support a predominant genetic influence on 3 H-imipramine binding.